/Engine/Source/Developer/DesktopPlatform/Public/IDesktopPlatform.h
Attempt to get the engine version from the supplied engine root directory. Tries to read the contents of Engine/Build/Build.version, but scrapes information from the Engine/Source/Launch/Resources/Version.h if it fails.
true if the engine version was successfully obtained
bool TryGetEngineVersion ( const [FString](API\Runtime\Core\Containers\FString) & RootDir, [FEngineVersion](API\Runtime\Core\Misc\FEngineVersion) & OutVersion )